Issue #9544 has been reported by Jakub Szafranski.
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Bug #9544: Ruby resolver not using autoport
https://bugs.ruby-lang.org/issues/9544
* Author: Jakub Szafranski
* Status: Open
* Priority: High
* Assignee:
* Category: core
* Target version: current: 2.2.0
* ruby -v: ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-freebsd9.1]
* Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN
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### Problem
On one of my production servers I've noticed that customers were failing to install anything using gem and the latest ruby. After a bit of debugging we've found out, that it's related to ruby resolve module:
<pre>
> p Resolv.getaddress "google.com"
Errno::EPERM: Operation not permitted - bind(2) for "0.0.0.0" port 62374
from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:654:in `bind'
from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:654:in `bind_random_port'
from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:747:in `block in initialize'
from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:735:in `each'
...
</pre>
The interesting part is _bind_random_port_ function. What for? The standard way of binding to a random port for udp connection is to use port 0. And on that particular machine it fails because it's using a mac_portacl module to filter which user can bind to what ports. **However, port 0 is excepted from this rule, because it's the AUTOPORT** - practically every system that allows such port filtering also allows to set an exception for the autoport.
### Docs
<pre>
Purpose:
Port 0 is officially a reserved port in TCP/IP networking, meaning that it should not be used for any TCP or UDP network communications. However, port 0 sometimes takes on a special meaning in network programming, particularly Unix socket programming. In that environment, port 0 is a programming technique for specifying system-allocated (dynamic) ports.
Description:
Configuring a new socket connection requires assigning a TCP or UDP port number. Instead of hard-coding a particular port number, or writing code that searches for an available port on the local system, network programmers can instead specify port 0 as a connection parameter. That triggers the operating system to automatically search for and return the next available port in the dynamic port number range.</pre>
### Impact
This bug affects every system that has a restricted port-binding policy, making ruby unavailable for security-freak admins ;)
### Suggested fix:
Either use port 0 to bind to the port, or at least make an option for the system admin/end user to specify the port by himself.
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http://bugs.ruby-lang.org/